CN107107248B

CN107107248B - Method for producing a sandwich panel

Info

Publication number: CN107107248B
Application number: CN201580069297.XA
Authority: CN
Inventors: T·孚罗里西; S·林德纳
Original assignee: Outokumpu Oyj
Current assignee: Outokumpu Oyj
Priority date: 2014-12-18
Filing date: 2015-12-17
Publication date: 2022-07-29
Anticipated expiration: 2035-12-17
Also published as: CA2969909C; EA201791040A1; KR20190060013A; WO2016097186A1; BR112017012659B1; MX2017007877A; CA2969909A1; JP2018501984A; EP3034226A1; CN107107248A; BR112017012659A2; JP6810040B2; US10654123B2; KR102329647B1; MY191003A; US20170348789A1; EA038199B1; KR20170095347A; AU2015367352B2; AU2015367352A1

Abstract

The invention relates to a method for producing a sandwich panel as a semi-finished product, wherein at least one layer (2, 12) of a non-metallic material is located between at least two metal layers (1, 3; 11, 13). At least one of the metal layers (1, 3; 11, 13) is shaped as a three-dimensional layer (3, 13), and the metal layers (1, 3; 11, 13) are formed in direct mechanical contact, so that the semi-finished product can be resistance welded in order to connect the semi-finished product to a desired combination of solutions in a subsequent manufacturing process.

Description

Method for producing a sandwich panel

Technical Field

The invention relates to a method for manufacturing a sandwich panel as a semi-finished product, wherein layers of non-metallic material are positioned in recessed spaces between metal layers in such a way that the semi-finished product can be directly used by the subsequent processing industry for a soldering process, one of the metal layers being a substantially flat metal layer and the other metal layer being a three-dimensionally profiled metal layer.

Background

The sandwich plate structure may be made of a wide variety of metallic, polymeric or composite materials. Many sandwich plate structures have been found to reduce weight and noise and provide sufficient stiffness and strength for structural load support. Sandwich panels with a core relative density of 2 to 10% and cell sizes in the millimeter range were evaluated for use as multifunctional structures. The open and three-dimensional pore network of the lattice support structure creates the opportunity to support both high stresses and cross-flow heat exchange. Due to the above-mentioned advantages, in particular the light weight and stiffness properties, sandwich panel structures are of interest for a wide range of processing industries, such as automotive engineering, commercial, agricultural and railway vehicle, marine and building construction or container engineering. Complex manufacturing processes are often necessary and the accepted and trained cost-effective and process-effective methods for monolithic sheet metal (e.g., steel) cannot be used. This is particularly true for welding processes such as resistance welding.

For resistance welding in general and spot welding in particular as a method of resistance welding process, joule's law of resistance heating in physics is used. This means that electrical energy is converted into ohmic resistance and then further into thermal energy. This means for the spot welding process that current flows in the circuit. The machine parts are made of copper in order to transmit the current well with low electrical resistance and low heat losses. At the transition point from copper to metal sheet, between sheets and from the second sheet to copper, the energy of the current is converted into ohmic resistance. The thermal energy is highest at this point, due to the effect that the transition resistance between the two sheets is highest until now. Finally, the heat energy at this point reaches the melting temperature of the sheet and creates a weld or so-called weld nugget. The formula for the heat energy is: q Is ═ Is ² And t R, wherein Is the welding current, t Is the welding time, and R Is the sum of all resistances. When using existing sandwich plate structures, there is at least one non-metallic material that is insulating. Thus, the circuit is not closed and the heat energy to fuse the sheets together cannot be generated.

Data sheets for tower steels or steels in WO publication Nos. 2014009114A1, 2014001152A9 and 2013156167A1

unique and durable composite solution that delivers light-weight products and design innovation》(

Unique durable composite solutions providing lightweight products and design innovations) mention typical sandwich panels with flat sequences of different layers. Furthermore, WO publications 2008125228a1 and 2004002646a1 describe a method for producing a metallic sandwich structure with different layers bonded together. All these WO publications have the same disadvantage of having insulating material between the metal outer layers, resulting in unsuitable resistance welding.

Japanese publication H01-127125 describes a method for manufacturing a sandwich panel comprising two metal layers of thin sheets and a corrugated element. Spot welding is used to assemble the first sheet metal layer to one surface of the corrugated strip. Then, an adhesive tape treatment is performed. A pair of rollers are used to assemble the second sheet metal layer onto the second surface of the corrugated strip by pressing and bonding. The resulting semifinished product has the disadvantage that subsequent processing industries, such as body manufacturers, cannot use the sandwich product for further resistance welding processes in order to join the sandwich panel with other body sheets, plates or formed parts. The reason is that the mentioned strip acts as an insulator of the electrical circuit in the resistance welding process. Solder nuggets cannot be generated and thus connections cannot be established.

Japanese patent publication H0278541A describes a method of how to produce a sandwich structure in which depressions are produced on the outer surface of one metal sheet in a laminate formed by inserting resin. This is achieved in that the distance between the tip of the projection and the inner surface of the other metal sheet is given by this distance. This means that despite the use of shaped outer steel sheets, there is finally a defined insulation gap between the two metal sheets, resulting in an unsuitable arrangement for resistance welding.

Us patent application 2013-273387 relates to high frequency welding of laminated metal sheets. Thus, a first composite sheet metal part comprising at least two metal sheets and a sheet arranged between the two metal sheets, which consists of a material having a composition different from that of the two metal sheets, is welded to a second sheet metal part consisting of a solid metal material or other composite material, which has at least two metal sheets and a sheet arranged between the metal sheets, which consists of a material having a composition different from that of the two metal sheets.

WO publication 2011082128a1 mentions a method of welding sandwich panels by resistance spot welding, wherein the composite core material of the sandwich panel is laminated by two metal outer layers. The goal of creating a particular resistance weld suitability is addressed by having a plurality of steel fibers in the core layer in electrical communication with the outer sheet steel. One disadvantage is the reproducibility and repeatability of the welding results. When a subsequent manufacturer wants to use welding parameters, it cannot be guaranteed that there is a correct and sufficient number of steel fibres in contact. There is a great risk that: weld spatter is generated in the contact area of the steel fibers with the outer layer of steel and burns the non-metallic components surrounding it. In addition to softening and displacing the non-metallic interlayer, mention is also made in the following publications and in the content of the detailed description thereof as a way of solving this object.

In order to circumvent the disadvantages of resistance welding unsuitable sandwich structures, there are different patents describing processes and methods relating to how to make sandwich structures that are not weldable in the initial semi-finished delivery state configuration weldable in specific further processes. One example is japanese laid-open publication 2006305591a in which two metal outer layers are laminated on the surfaces of both of them with a thermoplastic resin insulating sheet. The purpose of bringing the two metal layers into direct contact is solved by softening the resin insulating plate and by pushing it outwards out of the welding position. The two welding electrodes must be in a heated state, which is costly, requires special equipment for the manufacturer, and is implemented in the subsequent processing industry. DE publication 102011054362a1 discloses another particular way relating to how interlayer products unsuitable for resistance welding can be made weldable in a particular configuration using additional processing steps during the manufacture of the component. This task is solved by heating the plastic core layer in a first process step and then imparting a force to the surface of the interlayer with at least one electrode in a second process step. The softened non-metallic middle layer will move away from the force loading position and the two metallic outer layers come into contact. Both steps are additional processing steps in the component manufacturing process, requiring additional production time, increasing manufacturing costs, and reducing clock cycles. Furthermore, it is mentioned that this solution is only applicable to certain boundary regions of the component. The same additional processing step is solved by DE publication 102011109708a1, which also describes a subsequent processing in order to render weldable the sandwich structure in which the two outer metal layers are not in direct contact in the initial state. FR publication 2709083a1 describes a typical sandwich panel having two outer sheets of metal and a non-metallic core material separating the two outer sheets. To achieve a particular weldability, the same method as in DE publication 102011054362a1 is used to soften and remove the non-metallic core material at the boundary area of the sheet.

Another extensive and complicated method of producing circuits for resistance welding of unsuitable sandwich panels is described in WO publication 2012150144a 1. The task here is to build up a bridge with additional machine parts in order to bypass the insulating polymer material and to achieve weldability of the sandwich panel with other sheets. Additional time is required to install a very large amount of hardware (which limits accessibility to the sheet) and position it in the correct location. This increases the production cost. Especially for large components formed, it would be problematic to create electrical contacts with the problem of undefined electrical currents.

There are other sources of literature, such as papers seeking other joining methods to replace resistance welding. Alexander Kempf drafted a paper entitled "study of mechanical joining method of sandwich material" at aachen industry university in 2004. In a paper by Gunther Lange entitled "study of the forming behaviour of a three-layer austenitic sandwich composite with a polymer core" (TU claustral, 2005), an overview of possible joining methods is given: only the lap joint using brazing, bonding or laser beam is described. No mention is made of a resistance welding process or a full penetration welding process.

Based on these publications, sandwich panels, which are a combination of two substantially planar metal layers and a non-metallic intermediate layer, are already known. However, the serious disadvantage of not giving suitability for resistance welding in the initial semi-finished product and in the delivery state is not solved. Subsequent component manufacturing cannot use its existing resistance welder or create full penetration by linear contact welding methods such as laser beam or plasma welding. A disadvantage of such sandwich panels is that the non-metallic layers electrically isolate the metallic layers. This makes it difficult to solder the interlayers to other materials and integrate them into components of the multi-material design.

Disclosure of Invention

The object of the present invention is to prevent some of the drawbacks of the prior art and to achieve an improved method for manufacturing a semi-finished sandwich panel having at least two metal layers and at least one non-metal layer between the metal layers. In the method, mechanical contact between the metal layers is performed by using a three-dimensional metal thin plate as at least one metal layer and filling a non-metal material into a recess space formed between the metal layers. The invention can now be used to apply the sandwich panel in its initial, delivered state directly to a subsequent welding process, in particular a resistance welding process, in a subsequent manufacturing process (e.g. body engineering), i.e. the metal layers of the sandwich panel are brought into direct mechanical contact, so that resistance welding suitability is possible. Another benefit of the present invention is the selected arrangement of the sandwich panels: in contrast to the prior art, where a sandwich panel comprises two (metal) outer layers and two adhesive layers for bonding the two outer layers to an intermediately positioned core material, the invention uses in the simplest way only two metal layers, one of which is substantially flat and the other substantially three-dimensional, and one non-metal adhesive layer, which fills the recessed space between the two metal layers. As a result, the sandwich panel of the invention can be manufactured using a relatively simple production line, increasing the clock frequency, and it is relatively cheap, because two layers are saved compared to prior art sandwich panels. The essential features of the invention are set forth in the appended claims.

According to the invention, the sandwich panel is made of at least two metal layers and at least one non-metal layer, which is located in a recessed space formed between the two metal layers when the at least one metal layer is shaped into a three-dimensional object. The non-metallic composite material is filled into the recessed space formed between the two metal layers with a degree of filling of at most 60%, preferably at most 90%, most preferably at most substantially 100%. To apply the non-metallic material, one or more fine nozzles are used to ensure the desired degree of filling. In the present invention, a doctor blade may be used to trim non-metallic material from the potential contact area, but this is not preferred. The three-dimensional metal layer can optionally be heated up to 80 ℃ to increase the flow behavior of the filled non-metallic material. Advantageously, the viscosity confirmed is about 10000 mPas. For clarity, when referring to metal layers in this specification, a two-dimensional metal layer is referred to as a first metal layer and a three-dimensional metal layer is referred to as a second metal layer.

The non-metallic layer according to the invention is located substantially in the valleys of the second metallic layer. The metal peak surfaces of the second metal layer are substantially in direct mechanical contact with the first metal layer. The direct mechanical contact between the first metal layer and the second metal layer also ensures electrical contact. The electrical contact further enables the sandwich panel to have an electrical circuit and thus to join the sandwich panel with other sheets, plates or shaped pieces by resistance spot welding or other welding processes in order to connect the semi-finished product to the structure of the desired combination of solutions. The form of the three-dimensional layers in combination with the selected non-metallic material and the degree of filling of the non-metallic material in the recessed spaces formed between the metallic layers are such that the sandwich panels have their mechanical, stiffness, acoustic, bonding and handling characteristics.

The first and second metal layers in the manufacture of the sandwich panel according to the invention are advantageously made of the same material (e.g. stainless steel, carbon steel, copper, aluminium, magnesium), but the first and second metal layers may also be made of different metal materials, different metals or different metal compositions. When different metals or different metal compositions are used, the combination of these metals may further alter the behaviour of the sandwich panel. For example, a combination of metals with different coefficients of thermal expansion is advantageous in some solutions of the invention. The thermal expansion of the sandwich panel can be influenced by using two metals having two different thermal expansion coefficients, and the surface of the three-dimensional sheet will avoid damage to the welded area of the sandwich panel. Furthermore, the sandwich panel according to the invention with two different metal layers can be used as a component bridge in the wet corrosion region of a vehicle body of a multi-material design. For example, the king-post foot is made of stainless steel and the rocker rail is made of aluminum, and a sandwich plate can be used as a connection between these two components. The aluminium side of sandwich panel welds on the aluminium rocker track, and stainless steel intermediate layer and stainless steel center pillar welding. Thus, there is no contact corrosion and electrochemical potential bridges between the different components. The only potential bridge is now in the sandwich panel, but the non-metallic layers separate a large area, while the remaining metallic contacts are small compared to the component dimensions (linear or point contacts).

The second metal layer in the sandwich panel produced according to the invention is a corrugated metal piece, a metal piece in the shape of a nodule, pimple on the surface of the second metal layer, or any other three-dimensional metal piece which can be mechanically connected to the substantially flat two-dimensional first metal layer. Suitable shapes for the second metal layer can be found, for example, in WO publication 2014/096180. The form of the second metal layer also determines the damping, noise, vibration, stiffness (in particular the buckling stiffness) and solderability of the sandwich panel. The sheet of pimple and nub profile results in a stiffness that is independent of direction, but is only suitable for welding by resistance spot welding (due to the point contact). The corrugated profile sheet has a direction dependent stiffness but is rendered weldable (due to linear contact) in all continuous welding processes such as resistance roll seam welding. In case the shape of the second metal layer is corrugated and depends on the solution with sandwich panels, the second metal layer may have a substantially sinusoidal wave shape or the second layer may have the shape of a corrugated strip where two parts of the strip adjacent to each other are substantially perpendicular to each other. Corrugated strips of other shapes may also be used for the second layer in a sandwich panel manufactured according to the invention.

The non-metallic layer between the two metallic layers in the sandwich panel of the invention is advantageously made of a polymer material, a resin material, a cold or hot set one or two component adhesive glue (e.g. a crash resistant one component adhesive glue for the automotive industry or a two component sandwich adhesive material containing a resin and a hardener). Important characteristics of the non-metallic interlayer are the viscosity at the time of application and the manner of curing and foaming. A good viscosity to reach a defined filling degree without destroying the metal contact area is about 10000 mPas. Depending on the non-metallic material, preheating the non-metallic material prior to application may be appropriate to achieve the correct application viscosity. The manner of curing and foaming depends on the adhesive selected: one way is to use a sealant that reacts upon contact with a water spray and the other way is to use a two-component adhesive material that reacts to temperature. Typical interlayer adhesive materials (e.g., two-component polyurethane adhesives in combination with a hardener) are also possible and suitable. After mixing the resin with the curing agent, a defined application time is given to apply all interlayers.

When manufacturing a sandwich panel according to the method of the invention, the second metal layer, which consists of a continuous metal piece or metal layer element, is preferably placed in a substantially horizontal position. Naturally, any position between the substantially horizontal position and the substantially vertical position may be employed. In the case where the second metal layer is placed in a substantially horizontal position, the material for the nonmetal layer is embedded in the concave space formed on a portion between the metal layers, which is located at a lower position with respect to the vertical direction of the surface of the second metal layer. The total amount of material for the non-metallic layers is such that at most 60%, preferably at most 90%, most preferably at most 100% of the recessed spaces formed between the metallic layers are filled with material for the non-metallic layers. With a defined degree of filling, the weight, stiffness, fatigue, noise and damping properties of the sandwich panel can be varied to meet the desired solution. The upper part of the surface of the second metal layer (in the vertical direction) is free of non-metallic layer material. In the manufacture of the sandwich panel, the regions on the surface of the second metal layer which are free of non-metal layers achieve mechanical contact between the metal layers.

The first metal layer is transferred for manufacturing the sandwich panel according to the invention such that the first metal layer is above the second metal layer and thus also above the non-metal layer. The mutual position between the first and second metal layers is advantageously such that the non-metal layer is arranged transversely with respect to the two metal layers. The mechanical contact is realized between the first metal layer and the second metal layer. The mechanical contact is achieved on a specific area of the upper surface of the second metal layer (which area is not covered by the non-metallic layer, the uppermost part of the second metal layer in the vertical direction being able to interrupt the non-metallic layer material), or by means of a specific member located on the upper part of the second metal layer.

The first and second metal layers in the sandwich panel of the invention are attached to each other by a combination of adhesive and metal contact, so that the welding (in order to connect the semi-finished product to the structure of the desired combination of solutions) to other sheets, plates or forms will focus on the point where the first and second metal layers have structural mechanical contact with each other. The mechanical contact between two metal surfaces enables the use of different kinds of ways of having an electrical circuit between said surfaces.

Welding of the first metal layer and the second metal layer (in order to connect the semi-finished product to the structure of the desired combination of solutions) to other metal sheets, plates or formed pieces can be done by electric welding, projection welding, pinch welding or roll seam welding as an electric resistance welding process. Other welding processes (e.g., microplasma welding and laser micro-welding) as well as seam welding processes (e.g., electron beam welding and laser beam welding) may also be utilized.

The sandwich panel according to the invention is also constructed such that it can be joined to a desired piece of material in order to connect the sandwich panel to a complete structure, such as a car body. Sandwich panels are used in subsequent manufacturing processes, for example in the body construction of passenger cars, commercial vehicles, agricultural vehicles or railway vehicles, in particular for wet-area components or components such as car roofs, hoods/frontwalls, channels, pillar inserts, front covers or for noise-related applications (e.g. containers).

Drawings

The invention is described in more detail with reference to the following drawings, in which:

fig. 1 shows a preferred embodiment of the invention in a schematic way from a side view, while

Fig. 2 shows a further preferred embodiment of the invention in a schematic way from a side view.

Detailed Description

Shown in fig. 1 are a flat metal layer 1, a polymer layer 2 and a three-dimensional metal layer 3. The polymer layer 2 is located in a recess space formed between the metal layers 1 and 3.

In fig. 2, the planar metal layer 11, the polymer layer 12 and the three-dimensional metal layer 13 are similar to the layers described in connection with the description of fig. 1. The sandwich of

metal layers

11 and 13 and polymer layers is welded to a metal sheet 14 by resistance spot welding 15.

Claims

1. A method for manufacturing a sandwich panel as a semi-finished product, the method comprising: providing a first metal layer and a second metal layer, wherein the second metal layer is shaped as a three-dimensional layer having recessed regions and raised regions; the recessed region of the second metal layer is at least partially filled with a non-metallic material, and at least a portion of the raised region of the second metal layer is free of the non-metallic material; a surface of the second metal layer in which the recessed region has been at least partially filled with a non-metallic material is covered with the first metal layer such that the non-metallic material is disposed between the first and second metal layers; the recessed region is at least partially filled to a desired degree of filling with a nozzle; the first metal layer is bonded to the second metal layer, the at least a portion of the raised area of the second metal layer free of non-metallic material and the first metal layer being in contact with one another such that the semi-finished product is capable of being resistance welded to join the semi-finished product to at least a portion of a metal product in a subsequent manufacturing process.

2. The method of claim 1, wherein the non-metallic material is positioned in the recessed area with a variable degree of filling up to 60%.

3. The method of claim 2, wherein the degree of filling is at most 90%.

4. The method of claim 2, wherein the degree of filling is at most 100%.

5. The method according to any of the preceding claims 1 to 4, wherein the non-metallic material is made of a polymeric material.

6. The method according to any of the preceding claims 1 to 4, characterized in that the non-metallic material is made of a resin material.

7. A method according to any of the preceding claims 1-4, characterized in that the non-metallic material is made of one or two-component adhesive glue that is cold-set or hot-set.

8. A method according to any of the preceding claims 1-4, characterized in that the non-metallic material is made of a two-component sandwich adhesive material comprising a resin and a hardener.

9. Method according to any of the preceding claims 1-4, characterized in that the semi-finished sandwich plates are joined by welding in a subsequent manufacturing process in order to connect the semi-finished products to the desired combination of solutions.

10. Method according to any of the preceding claims 1-4, characterized in that the semi-finished sandwich panel is joined by resistance spot welding in a subsequent manufacturing process in order to connect the semi-finished product to a desired combination of solutions.

11. A method according to any one of the preceding claims 1 to 4, characterised in that the semifinished sandwich panels are joined by resistance seam welding in a subsequent manufacturing process in order to connect the semifinished products to a desired combination of solutions.

12. Method according to any of the preceding claims 1 to 4, characterized in that the semifinished sandwich panels are joined in a subsequent manufacturing process by laser beam welding or electron beam welding in order to attach the semifinished products to the desired combination of solutions.

13. Method according to any of the preceding claims 1 to 4, characterized in that the semi-finished sandwich panel is joined in a subsequent manufacturing process by micro-plasma welding in order to connect the semi-finished product to a desired combination of solutions.